The invention relates to a motor vehicle seat with a) an underframe with b) a seat carrier that is height-adjustably connected to the underframe through a left rear oscillating crank and through a right rear oscillating crank, with c) a catch device which is directly assigned to one of the two rear oscillating cranks and permits to adjust and lock the angular position of said crank relative to the underframe, with d) a non-rotatable tie bar that joins the two rear oscillating cranks so that they are parallel when the vehicle seat is subjected to normal load, with e) a retaining device having a sector gear firmly connected to the other one of the two rear oscillating cranks, an engaging piece which is movably disposed on the seat carrier or on the underframe, is provided with teeth devised for engagement with the sector gear and is disengaged from the sector gear when the vehicle seat is subjected to normal load, and an actuator that is activated when the associated motor vehicle is subjected to a crash load and causes the engaging piece to move into positive mesh with the sector gear.
A motor vehicle seat of this type is described in PCT/EP 00/10692. EP 0 577 517 B1 shows a similar vehicle seat. The first mentioned reference describes what is termed a crash stop that is activated when a load limit is exceeded, a change in the geometry of a height-adjuster for example being taken into consideration for sensing a load limit. Two crash stops are suggested, the one crash stop becoming active for positive accelerations of the seat such as during rear collisions. The other crash stop is activated for negative accelerations as they are typical with frontal crashes.
EP 0 577 517 B1 describes a hinged oscillating lock whose excursion in accident situation is utilized to block a joint so that a crash stop may engage.
These previously proposed crash stops have the disadvantage that the respective accident situation of the vehicle seat is sensed by special elements that are associated to the respective one of the crash stops only. Said elements must be devised and sized in such a manner that they reliably react in the most varied accident situations, e.g., during a vehicle collision in the direction of a diagonal of the vehicle. It must further be made certain that the locking occurs early enough in case of a crash, i.e., before the parts were able to move relative to one another. It is thus made certain that the joint regions need not deform prior to engagement of a stop. Deformation prior to said engagement is critical, particularly because it may occur in different ways depending on the direction of the crash so that reliable locking cannot always be achieved in an accident situation.
The invention is directed to such type vehicle seats that have a catch on one side. One of the two rear oscillating cranks is directly assigned a catch device. Through the non-rotatable tie bar the other rear oscillating crank is retained in the same angular position as the rear oscillating crank which is provided with the catch device. This construction permits easy, light-weighted and secure configuration and immobilization of the vehicle seat under normal operating conditions. It is thus not necessary to transmit the adjustment of the catch to the other seat side and to provide the latter with a complete catch device.
In such vehicle seats, the catch of the directly immobilized rear oscillating crank may be configured using appropriate measures in such a secure manner that it is kept immobilized during an accident. For an example, the reader is referred to the documents DE 199 44 866.3 and DE 100 20 923.8.
In accident situations however, that side of the seat which is not directly immobilized must be additionally locked or otherwise secured to prevent it from deforming more than the directly locked seat side during an accident. Crash stops are suited for this purpose.